libjpeg-turbo is a derivative of libjpeg that uses MMX, SSE, SSE2,
and NEON SIMD instructions to accelerate baseline JPEG
compression/decompression by about 2-4x on amd64, arm and x86
platforms. It is based on libjpeg/SIMD but has numerous enhancements.

that's right, there isn't any optimization for powerpc or altivec simd.
Jpeg optimizations with AltiVec exists only on macosx for powerpc._________________LinuxPPC user!
my blog: http://linuxpowerpc.blogspot.com/

What does that mean for us? The only sentence about PPC I could found in the web was:

Quote:

libjpeg-turbo works on powerpc, but doesn't get any speedup over regular libjpeg.

Is that still correct?

Where did you find this statement? In any case, it does not matter You can easily run some jpeg decoding benchmarks with any image yourself. For example, on my playstation3 (with CFLAGS="-g -mcpu=cell -mtune=cell -maltivec -O2 -fomit-frame-pointer -pipe"):

Yes, libjpeg-turbo clearly can't be 2-4x times faster on PPC without altivec optimizations. But it still has some non-SIMD performance optimizations too (primarily huffman), which should give it some advantage on any platform.